+namespace llvm {
+/// \brief Make MDOperand transparent for hashing.
+///
+/// This overload of an implementation detail of the hashing library makes
+/// MDOperand hash to the same value as a \a Metadata pointer.
+///
+/// Note that overloading \a hash_value() as follows:
+///
+/// \code
+/// size_t hash_value(const MDOperand &X) { return hash_value(X.get()); }
+/// \endcode
+///
+/// does not cause MDOperand to be transparent. In particular, a bare pointer
+/// doesn't get hashed before it's combined, whereas \a MDOperand would.
+static const Metadata *get_hashable_data(const MDOperand &X) { return X.get(); }
+}
+
+unsigned MDNodeOpsKey::calculateHash(MDNode *N) {
+ unsigned Hash = hash_combine_range(N->op_begin(), N->op_end());
+#ifndef NDEBUG
+ {
+ SmallVector<Metadata *, 8> MDs(N->op_begin(), N->op_end());
+ unsigned RawHash = calculateHash(MDs);
+ assert(Hash == RawHash &&
+ "Expected hash of MDOperand to equal hash of Metadata*");
+ }
+#endif
+ return Hash;
+}
+
+unsigned MDNodeOpsKey::calculateHash(ArrayRef<Metadata *> Ops) {
+ return hash_combine_range(Ops.begin(), Ops.end());
+}
+